Gas film lubrication method on rotation shaft seal based on contact design

Purpose Wear failure happens frequently in rubber seal of high-speed rotating shaft because of the dry friction. Some traditional lubrication methods are not effective because of the restrictions on the relative high speed, temperature and others. This paper aims to present a new method of lubrication with gas film for the rotation shaft seal based on the contact design. Design/methodology/approach To obtain the generation condition of gas film and good effect of lubrication in the contact gap between the shaft and its seal, a series of micro-spiral grooves are designed on the contact surface of rubber seal so as to obtain a continuous dynamic pressure difference. Findings The result is that the distribution of the gas film in the micro-gap is continuous under the design of the spiral grooves and the contact with eccentricity because of the deformation of rubber seal, which is verified through the simulation calculation and experiment test. It is confirmed that the lubrication method with gas film through designing micro-spiral grooves on the contact surface is effective, and can achieve self-adaptive air lubrication for the high-speed shaft under the premise of the reliable sealing. Originality/value The method of gas film lubrication is realized through designing a microstructure of spiral grooves on the rubber surface to change the contact status, which can form a mechanism of adaptive lubrication to reduce the dry friction automatically in the contact gap. For the cross-scale difference between the rubber seal and gas film, a new modeling method is presented by building the mapping relation for the split blocks and repairing technique with integrated computer engineering and manufacturing, to reduce the possibility of nonconvergence and improve the efficiency and accuracy of calculation.

An Innovative Elasto-Hydrodynamic Seal Concept for Supercritical CO2 Power Cycles

Supercritical CO2 (sCO2) power cycles are promising next generation power technologies, holding a great potential in fossil fuel power plants, nuclear power production, solar power, geothermal power, and ship propulsion. To unlock the potential of sCO2 power cycles, technology readiness must be demonstrated on the scale of 10–600 MWe and at sCO2 temperatures and pressures of 350–700 °C and 20–30 MPa for nuclear industries. Amongst many challenges at the component level, the lack of suitable shaft seals for sCO2 operating conditions needs to be addressed for the next generation nuclear turbine and compressor development. In this study, we propose a novel Elasto-Hydrodynamic (EHD) high-pressure, high temperature, and scalable shaft seal for sCO2 turbomachinery that offers low leakage, minimal wear, low cost, and no stress concentration. The focus in this paper was to conduct a proof-of-concept study with the help of physics-based computer simulations. The results showed that the proof-of-concept study was successfully demonstrated, warranting further investigation. Particularly, it was interesting to note the quadratic form of the leakage rate, making its peak of m ˙ = 0.075 kg/s at Pin = 15 MPa and then decaying to less than m ˙ = 0.040 kg/s at Pin = 30 MPa, suggesting that the proposed seal design could be tailored further to become a potential candidate for the shaft seal problems in sCO2 turbomachinery.

Analysis of Fluid Flow in the Sealing Gap of Radial Shaft Seals and Elastic Deformation of the Sealing Surface

The function of a radial shaft seal bases on interactions between the sealing edge and the shaft counterface. To better understand these mechanisms, a look inside the sealing contact was taken. The procedure and the testing facility are presented in this paper. In addition, a research methodology was developed, to systematically analyse the fluid flow and the distortion of the sealing surface of shaft seals. The results of the test procedure are documented in an evaluation matrix that allows the comparison of sealing systems with different worn sealing edges. For example, the tests show an influence of the rotation direction of the shaft during running-in on the formation of leakage channels or oil collecting chambers within the sealing contact.

Effective strain range-based prediction and analysis of the fatigue life of pipette shaft seal ring

The accuracy of nucleic acid extraction and diagnosis depends on the sealing performance of the pipetting device. The rubber seal ring at the front end of the pipette shaft is a critical component for ensuring the sealing performance of the pipetting device. In this study, an accurate prediction and analysis were made on the fatigue life of the pipette shaft seal ring. ABAQUS was used to simulate the assembly process of pipette shaft seal ring and disposable tip, and the dangerous cross-section segments on the seal rings were preliminarily identified according to a stress nephogram. Based on the continuum damage mechanics theory, the fatigue life prediction model was built where the effective strain was taken as a damage parameter, and the fatigue life of the dangerous cross-section of the pipette shaft seal ring was calculated. By observing failed seal rings in actual use, it was found that the worn positions of the failed seal rings were the same as the sites of the shortest-lived node segments, thus verifying the accuracy of fatigue life prediction model and fatigue life analysis.